<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"> <!--键值对，key=value-->
<title>网页tab的title</title>
<script src='texiao.js' type='text/javascript'></script>
</head>

<body>
<div>
<h1 id='title'>web开发</h1>
<label for=text>输入文本</label>
<input type="text" id='hello' placeholder="文本存储于属性.value">
<div>

<button onclick="add_tag('事件操作', 'h2')">新增标题</button>
<button onclick="print_text()">打印文本</button>
</body>